Don't forget the Glock .45 barrels, in addition to having polygonal rifling, also have an octagonal profile, creating a slightly better gas seal. Expect a little more velocity vs. standard rifling in an identical length barrel. I've read a chrono test of the Speer Gold Dot 200 gr. +P out of a Glock 30. It chronographed at 1017 fps! That's pretty darn good considering this round is rated at 1080 fps out of a 5" barrel.
Last edited by WinterWizard; 03-13-2012 at 19:33..
The Glock 30 and 36 3.78" barrels are long enough to generate adequate velocity in SD ammo.
Polygonal barrels add very minimal velocity increases, if any. Here is an objective comparison where the rifled barrel of the same length had higher velocity than poly: http://gunblast.com/Kahr-45s.htm